1. Field of the Invention
The present invention relates to radio frequency antennas. More particularly, the present invention relates to low cost HDTV television antenna with impedance matching for a loop element.
2. Description of the Related Art
Prior art television antennas fall into two general categories, the indoor antenna and the outdoor antenna. Indoor antennas are sometimes referred to as set-top antenna, and outdoor antennas are commonly mounted to a mast located above the rooftop of a home or other building. Since US television broadcasts have occurred on both the VHF band (54 MHz to 216 MHz) and the UHF band (470 MHz to 890 MHz), prior art antenna structures have been designed to receive in both of these bands. In fact, most prior art antenna systems have included two antenna structures, one for each band. For example, a common type prior art indoor antenna includes a 7.5″ loop antenna for the UHF band and a pair of telescopic dipole elements for the VHF band. The transition to High Definition Television (hereinafter “HDTV”) has altered the frequency band utilization. The original US television standard was promulgated as the NTSC standard (National Television System Committee) in 1941, and is well known to those skilled in the art. The United States has since promulgated a new standard, called the ATSC (Advanced Television Systems Committee), which is a digital broadcast format, commonly referred to as HDTV (High Definition Television). The ATSC standard has now been fully implemented in the United States. Additionally, over the decades, the frequency bands have becomes more narrowly defined. For example, the higher UHF channels from 69-83 were reallocated in the 1980s to land mobile radio, which narrowed the UHF TV band to 470 MHz to 806 MHz. Additionally, UHF channels 52-69 have been reallocated, again narrowing the band to 470 MHz to 698 MHz. In a similar vein, the VHF band is also being more narrowly used. The VHF band actually consists of two separate frequency bands, VHF-Low channels 2-6 (54 MHz to 88 MHz) and VHF-H channels 7-13 (174 MHz to 216 MHz).
This changes in frequency utilization and modulation techniques have also affected the required performance from TV antenna systems. This is due to the nature of digital modulation and demodulation, particularly the nature of the demodulation and its effect on subjective reception performance. In prior art NTSC analog television, a gradual reduction in received signal strength resulted in a gradual reduction in received audio and video quality, where acceptability for viewing is subjective in nature. However, in the case to HDTV under the newer ATSC digital modulation, gradual signal level reduction results in the crossing of an abrupt threshold from clear audio and video reception to a sudden and complete loss of received information. Also, generally speaking, HDTV requires a somewhat stronger received signal level to provide comparable performance as compared to analog demodulation. Thus, the transition from the NTSC standard to the ATSC standard has placed a greater demand for improved antenna performance.
The greater demand for antenna performance has not mitigated end user desire for affordability and convenience. This explains why set-top antennas remain in high demand, ostensibly for theirs low cost and convenient installation process. Even though it is well know that a set-top antenna will generally provide smaller received signal strength than a roof-top antenna. Thus, it can be appreciated that there is a need in the art for an improved TV antenna apparatus having enhanced performance and adapted to the new ATSC standard, while still providing the affordability and convenience desired by end users.